Sprue for molding apparatus



May 29, 1962 R. EDGERTON SPRUE FOR MOLDING APPARATUS Filed March 30,1960 R0440; [065R ro/v ATTORNEY United rates I 3,036,349 Patented May29, 19612 free 3,036,349 SPRUE FOR MOLDING APPARATUS Rollie Edgerton,1603 13th St., Boone, Iowa Filed Mar. 30, 1960, Ser. No. 18,740 1 Claim.(Cl. 22162) This invention relates to molding apparatus generally andmore particularly to an improved molding sprue for use during a foundrymold packing operation.

During the typical foundry molding operation, a pattern plate supportingthe pattern to be reproduced is placed at the bottom of a container ormold flask. This flask is then filled with sand which is placed underpressure, so that it will be compacted around the patternpro vided onthe pattern plate. When the pattern plate is removed, the pattern to bereproduced will remain imprinted in the sand, and the sand will thusform a mold for the casting operation. It is necessary toplace aremovable sprue in the sand prior to the compressing operation, so thata passage through the sand to the mold cavity is formed for the moltencasting material utilized.

The necessity for providing a removable sprue in the sand mold to form apassage to the pattern plate has presented numerous problems, for whenpressure is applied to compress the sand within the flask, pressure isalso applied to the sprue. When single piece rigid sprues are utilized,if the sprue does not conform exactly to the height of the flask,pressure applied thereto might result in damage to both the patternplate and the sprue itself. In a normal foundry operation, patterns andpattern plates of various sizes and thicknesses are utilized, and theflasks used therewith must therefore vary in size and height. Whensingle piece rigid sprues are used for molding, an excessive number ofsprues is required, for a sprue which conforms in height to eachindividual flask must be provided.

In the past, numerous attempts have been made to overcome thedifliculties arising from the use of sprues in the foundry operation.The sprues of the prior art have been constructed from single solidpieces of rubber or other elastic material so that applied pressure doesnot damage the sprue or the pattern plate. These sprues, because oftheir solid construction, are not readily adaptable for use with flasksof widely varying heights. In an attempt to overcome this heightdifficulty, other sprues known to the prior art have been constructedfrom several pieces of non-elastic material which are held in atelescoping relationship by springs or other suitable connectingmembers. Although these sprues may be easily adjusted in length, and aretherefore adapted for universal usage, they do not possess theflexibility of the elastic sprue and are therefore subject to a greaterdegree, to damage and wear.

It is a primary object of this invention to provide an improved moldingsprue capable of withstanding the pressures of a foundry moldingoperation.

Another object of this invention is to provide a molding sprue having asingle piece outer body which will yield under pressure.

A further object of this invention is to provide a yieldable moldingsprue which will automatically accommodate, within certain limits,flasks of varying heights.

With the foregoing and other objects in view, the invention resides inthe following specification and appended claim, certain details ofconstruction of which are illustrated in the accompanying drawings, inwhich:

FIGURE 1 is a sectional detailed view in front elevation of the moldingsprue of the invention;

FIGURE 2 is a sectional view in front elevation of the sprue of FIGURE 1applied to a sand mold; and

FIGURE 3 is a sectional view in front elevation of the 2 sand mold ofFIGURE 2 with the molding sprue and pattern plate removed.

Referring now to FIGURE 1, the molding sprue of the present inventionindicated generally at 10, includes a one piece resilient body 11 ofrubber or other suitable yieldable material. Body 11 is flared outwardlyat one end to provide a tapered head section 12 at the upper portion ofthe molding sprue 10. A longitudinally extending core passage 13 isformed through the center of sprue body 11. Core passage 13 includes anupper section '14 which extends through the center of the tapered head12, and a lower section 15. The upper section 14 of the core passage islarger in diameter than the lower section, so that a shoulder 16 isformed at the junction of the upper and lower sections 14 and 15. Theenlarged upper section 14 of the core passage 13 is provided with aliner 17 of metal or other suitable material which is molded in placewithin the core section. Liner 17 extends upwardly within the coresection 14 from the shoulder 16 to a point below the top surface 18 ofthe tapered sprue head 12. The upper edge of the liner 17 forms a seat19, which supports an elastic plug member 20. Plug member 20 is of thesame diameter as the upper core section 14, and is constructed so thatwhen the plug rests upon seat 19, its upper edge is flush with the upperedge 18 of the tapered sprue head 12.

An elongated metal pin 21 having an enlarged head portion 22 extendsfrom outside of the lower portion of sprue body 11 through the lowersection 15 of core passage 13 and into the lower portion of core section14. The enlarged head portion of pin 21 rests upon the shoulder 16 so asto permit downward movement of the head section 12 when sprue body 11 iscompressed. A washer 23 is secured around the lower portion of pin 21 bywelding or other suitable means. Washer 23 is positioned so that itabuts the lower edge of sprue body 11 and holds the enlarged headportion 22 of pin 21 in contact with the shoulder 16. The lower portionof pin 21 which projects outwardly beyond sprue body 11 and washer 23,forms a stud 24 which, when inserted in an aperture provided in apattern plate, acts to hold the sprue 10 in place.

Referring to FIGURE 2, the sprue 10 of the present invention is shown inoperational position within a sand mold. The mold forming processconsists of placing a flask 25 upon a pattern plate 26 which supports apattern 27. A gate form 28 may be placed on top of pattern plate 26 toform a gate between the sprue 10 and the pattern 27. Both the gate form28 and the pattern plate 26 are provided with an aperture 29 to receivethe stud 24 of the sprue 10. With the sprue 10 in position, the flask 25is filled with molding sand 30. A squeezer board 31 is then placedacross the top of the flask so that it rests on the top surface of thesand, and the top edge 18 of the sprue 10. Pressure is then applied tothe squeezer board which in turn compresses the sand about the pattern27 and the sprue 10. As pressure is applied to the head 12 of the sprue10, the elastic body ll of the sprue will expand, concurrently withbeing contracted relative to the pin 21. Pin 21 insures that the spruebody 11 will not bend, but will instead bulge outwardly against the sand30. When the pressure is removed from the squeezer board 31, the body 11of the sprue contracts and returns to its normal shape so that the spruemay be easily withdrawn from the compressed sand mold.

If the sprue 10 is longer than the height of flask 25 so that the topsurface 18 of the tapered head 12 projects above the sides of the flask,the squeezer board 31 will contact the upper surface 18 of the head 12before contacting the surface of the sand 30. As pressure is applied tothe squeezer board, the yieldable elastic body 11 of the molding sprue10 will be compressed and contracted relative to the pin 21 so as tomove downwardly on the pin 21. Continued compression of the yieldablesprue body 11 causes the sprue to decrease in length until the squeezerboard 31 contacts the surface of the molding sand 30. Thus the moldingsprue automatically adjusts itself for use with flasks of varyingheights within the compression and extension limits of the 'sprue'. i V

, FIGURE 3 shows the sand mold 30 after thecornpression process has beencompleted and the pattern plate, pattern, gate form, and sprue have beenremoved.

Moltenmater'eial may now be poured through the aperture 10a formed bythe sprue. This molten material will flow from the aperture 10a throughthe gate 28a to the molded pattern 27a. i

It will be readily apparent to those skilled in the art that the presentinvention provides a suitable and effective molding sprue which isautomatically adaptable for use with molding flasks of varying sizes.This invention may besubject to numerousmodifications well within thepurview of the inventor who only in tends to be limited to aliberalinterpretation of the specification and appended claimr w Iclaim:

A molding sprue comprising a one piece body member of rubber, one endofwhich is flared outwardly to form a tapered head portion, said bodymember having a 1ongitudinal core passage provided centrallytherethrough, the core passage including an enlarged upper sectionextending centrally through said tapered head portion and a lowersection of smaller diameter than said upper section, a shoulder formedat the junction of said upper and lower sections, a liner providedwithin said enlarged upper section and extending upwardly from saidshoulder to a point below the outer extremity of said core passage, aplug member inserted in said core passage and supported by the upperedge of said liner, and an elongated pin extending through said lowersection and projecting from the body member at the end opposite to saidhead portion, the elongated pin being provided with an enlarged head atone end, and an integrally at tached washer member positioned inwardlyof the opposite end thereof in contact with the lower'end of saidresilient body member, the enlarged head of said elongated pin normallyresting on the shoulder at the junction of said upper and lower corepassage sections, to provide for the downward longitudinal movement ofsaid head portion, whereby when pressure is applied to said head portiontoward said washer member, said body member is longitudinally contractedand transversely expanded relative to said pin.

References Cited in the file of this patent UNITED STATES PATENTS275,332 Depew Apr. 3, 1883 411,962 Heaphy Oct. 1, 1889 968,799 ProwseAug. 30, 1910 1,001,887 Rothbone Aug. 29, 1911 2,275,806 Perazo Mar. 10,1942

